The long term objectives of this proposal are: (1) Basic research in the area of solid state chemical sensors, namely CHEMFETs, leading to understanding and utilization of unique features of these devices; (2) Biomedical applications of CHEMFETs namely for in vivo monitoring of electrolytes in biological fluids and ex vivo monitoring of electrolytes and gases. This proposal will also provide basic support to other research programs in terms of devices and transfer of know-how. The specific aims for this grant period include: (a) design/development of multisensor chip with integrated supporting on-chip electronics. This design will be done concurrently with the separately funded microencapsulation effort which is essential for making these devices commercially available; (b) development of rapid microtechnique based on potentiometric stripping for trace analysis of heavy metals (Pb, Cu, Cd) in biological fluids. In this work we shall use our recently developed electrostatically protected ISFET; (c) Basic study of Langmuir-Blodgettt films deposited on the CHEMFET gates. This work should lead to better understanding of the electrochemistry of olfaction and ion flux modulation by adsorbing molecules on lipid bilayer membranes; (d) As in the previous period our devices will be made available to non-profit organizations at no cost.